Pod2g, the person responsible for the upcoming UNTETHERED iOS 5.0 and 5.0.1 Jailbreak, has posted a blog post with the current status of the process. This Jailbreak has been in the works for the past few months and has had it's fair share of kinks in the road. Apple unfortunately patched Pod2g's exploit which he was working on, so he had to start from scratch. The older devices are doing just fine with this Jailbreak and now we have confirmation of another step forward for the A5 devices.
The founder of Cydia himself stepped in to help out Pod2g by supposedly giving him a missing piece of the puzzle. This is all Pod2g needed to complete a "perfectly stable Jailbreak". We should be seeing a Jailbreak for at least the non-A5 devices very soon with the Jailbreak for the iPhone 4S and iPad 2 coming shortly after. Stay tuned for the latest news on the Jailbreak!"OK, figured it out, the A5 cache is not a problem anymore.
I sorted it out by doing the untether in a single thread and by flushing all the dcache then all the icache in a row at a strategical point of the process.
It took me like a hundred of tests to find the key. Hard for the nerves.
For the tech guys, here is a link explaining issues related to self modifying code ( or code patching ) on the ARM platform : Caches and Self-Modifying Code - ARM Community
Another news : I discussed with @saurik today about the launchd boot process, and he's found one missing piece of the puzzle I needed to have a perfectly stable jailbreak. He's definitly one of the best iOS gurus out there. Thank you saurian!"
pod2g's iOS blog: No more cache troubles